Master information carrier, process for producing the carrier, and method and apparatus for recording master information signal on magnetic recording medium by using the carrier

Abstract

A master information carrier comprises a substrate whose surface has an embossed pattern corresponding to an information signal. At least a surface of the protruding portion of the embossed pattern is made of a ferromagnetic material. A method for writing an information signal into a sheet or disk magnetic record medium with a ferromagnetic thin film or coating is performed by putting the surface of the magnetic record medium into contact with the master information carrier so as to write a magnetized pattern corresponding to the embossed pattern of the master information carrier into the magnetic record medium.

What is claimed is:  
     
       1. A master information carrier for writing an information signal into a magnetic record medium, wherein an embossed pattern corresponding to the information signal is formed on a substrate, at least a protruding portion of the embossed pattern is composed of a ferromagnetic material layer having a saturation magnetic flux density more than 0.8 T, and the ferromagnetic material layer composing the protruding portion is not continuous between adjacent protruding portions, but divided by recessed portions. 
     
     
       2. The master information carrier according to  claim 1 , wherein an embossed pattern corresponding to a digital information signal is formed on a surface of the substrate, a cross section of the protruding portion along bit length direction of the digital information signal has a substantially trapezoidal shape with an upper side at a surface that is shorter than a lower side on the substrate, and a length difference between the upper and lower sides is not more than twice the height of the trapezoid. 
     
     
       3. The master information carrier according to  claim 2 , wherein curvature radii at edges of the upper side of the trapezoid are not more than a half of the upper side length. 
     
     
       4. The master information carrier according to  claim 2 , wherein a thickness of the ferromagnetic material layer at the protruding portion is not more than a half of the upper side length, so that the master information carrier is suitable for writing information into an in-plane magnetic record medium. 
     
     
       5. The master information carrier according to  claim 2 , wherein a thickness of the ferromagnetic material layer at the protruding portion is more than twice of the upper side length, so that the master information carrier is suitable for writing information into a perpendicular magnetic record medium. 
     
     
       6. The master information carrier according to  claim 1 , wherein an embossed pattern corresponding to a digital information signal is formed on a surface of the substrate, and a cross section of the protruding portion along bit length direction of the digital information signal has a substantially trapezoidal shape with an upper side at a surface that is longer than a lower side on the substrate. 
     
     
       7. The master information carrier according to  claim 6 , wherein a thickness of the ferromagnetic material layer at the protruding portion is not more than a half of the upper side length, so that the master information carrier is suitable for writing information into an in-plane magnetic record medium. 
     
     
       8. The master information carrier according to  claim 6 , wherein a thickness of the ferromagnetic material layer at the protruding portion is more than twice of the upper side length, so that the master information carrier is suitable for writing information into a perpendicular magnetic record medium. 
     
     
       9. A master information carrier for writing an information signal into a magnetic record medium, wherein an embossed pattern corresponding to the information signal is formed on a substrate, at least a protruding portion of the embossed pattern is composed of a ferromagnetic material layer having a coercive force not more than 40 kA/m in the inplane direction, and the ferromagnetic material layer composing the protruding portion is not continuous between adjacent protruding portions, but divided by recessed portions. 
     
     
       10. The master information carrier according to  claim 9 , wherein an embossed pattern corresponding to a digital information signal is formed on a surface of the substrate, a cross section of the protruding portion along bit length direction of the digital information signal has a substantially trapezoidal shape with an upper side at a surface that is shorter than a lower side on the substrate, and a length difference between the upper and lower sides is not more than twice the height of the trapezoid. 
     
     
       11. The master information carrier according to  claim 10 , wherein curvature radii at edges of the upper side of the trapezoid are not more than a half of the upper side length. 
     
     
       12. The master information carrier according to  claim 10 , wherein a thickness of the ferromagnetic material layer at the protruding portion is not more than a half of the upper side length, so that the master information carrier is suitable for writing information into an in-plane magnetic record medium. 
     
     
       13. The master information carrier according to  claim 10 , wherein a thickness of the ferromagnetic material layer at the protruding portion is more than twice of the upper side length, so that the master information carrier is suitable for writing information into a perpendicular magnetic record medium. 
     
     
       14. The master information carrier according to  claim 9 , wherein an embossed pattern corresponding to a digital information signal is formed on a surface of the substrate, and a cross section of the protruding portion along bit length direction of the digital information signal has a substantially trapezoidal shape with an upper side at a surface that is longer than a lower side on the substrate. 
     
     
       15. The master information carrier according to  claim 14 , wherein a thickness of the ferromagnetic material layer at the protruding portion is not more than a half of the upper side length, so that the master information carrier is suitable for writing information into an in-plane magnetic record medium. 
     
     
       16. The master information carrier according to  claim 14 , wherein a thickness of the ferromagnetic material layer at the protruding portion is more than twice the upper side length, so that the master information carrier is suitable for writing information into a perpendicular magnetic record medium.